Strip fastener

ABSTRACT

A fastener ( 10 ) is adapted to releasably fix a first element ( 12 ) and a second element ( 14 ). The fastener ( 10 ) includes a channel ( 22 ) having a plurality of spaced 5 lockers ( 28 ). The lockers ( 28 ) are movable into the channel ( 22 ). The fastener ( 10 ) also has a locking tongue ( 30 ), having a plurality of spaced blockers ( 32 ). The tongue ( 30 ) is movable within the channel ( 22 ) between a locked position in which the blockers ( 32 ) prevent movement of the lockers ( 28 ) into the channel ( 22 ) and an unlocked position in which the lockers ( 28 ) are not prevented from moving into o the channel ( 22 ).

FIELD OF THE INVENTION

This invention relates to a fastener. In particular, this inventionrelates to the type of fastener which may be manufactured in variouslengths and which is often referred to below as a “strip fastener”.

BACKGROUND OF THE INVENTION

Strip fasteners are convenient and effective to fasten panels, doors,windows and other elements and can provide a continuous seal.

Versions of strip fasteners were disclosed in the publishedspecification of International Patent Application No PCT/AU99/00185 andin particular in connection with FIGS. 25 to 39 of that specification.The contents of the International Patent Application are imported hereinby reference.

At least in some respects, the present invention may be regarded as adevelopment of the strip fastener disclosed in the Internationalapplication imported herein.

At least in some embodiments, the present invention deals with materialwhich contracts when activated. Further comments regarding examples ofsuch material are set out below. There are some problems which can beexperienced with such material and these problems are also discussedbelow. The present invention, at least in some embodiments, aims toovercome or alleviate these problems.

SUMMARY OF THE INVENTION

The present invention provides a fastener adapted to releasably fix afirst element and a second element, the fastener including:

-   -   a channel having a plurality of spaced lockers, the lockers        being movable into the channel; and    -   a locking tongue having a plurality of spaced blockers, the        tongue being movable within the channel between a locked        position in which the blockers prevent movement of the lockers        into the channel and an unlocked position in which the lockers        are not prevented from moving into the channel.

The first element and the second element may be any suitable element.One example of the first element is a fixed panel and one example of thesecond element is a removable panel, or closure, such as a door.However, the invention is not limited to these embodiments. The firstand second elements may be chosen from a wide range of forms.

The channel may have sides which are not contiguous with a base. In apreferred embodiment, the channel has two opposed walls and a base whichis not joined to the sides. Other configurations may be suitable.

Preferably, the channel has the plurality of spaced lockers on each oftwo strips which together form opposed walls of the channel. In thisembodiment, the lockers on each of the two strips are adapted to pivottowards the center of the channel or be maintained by the blockers inthe locked position.

The locking tongue is preferably movable longitudinally within thechannel. In an especially preferred embodiment, the locking tongueincludes a base which forms the base of the channel, being slidabletherein.

The blockers are preferably of similar dimension to the lockers.Similarly the spaces between adjacent blockers are preferably the sameas or similar to the spaces between the lockers. With thisconfiguration, when the tongue is moved to the unlocking position, thelockers are located adjacent the spaces between the blockers and may bepivoted towards the centre of the channel without restraint by theblockers. When the lockers are encased with the channel and the blockingtongue is moved into place, the parts of this fastener draw together,tensioning the joint.

The lockers and blockers are preferably of metal so as to provide astrong arrangement for high load applications. It is also possible forthe lockers to be made of suitable engineering plastic, for lower loadrequirements. Appropriate material choices for specific applicationswill be apparent to one skilled in the art.

Preferably, the lockers move pivotally. In one embodiment, where thespaced lockers are on two strips which together form opposed walls ofthe channel, the lockers move pivotally when tops of the lockers tiltinwardly towards each other, into the channel. In another embodiment,the lockers form parallel walls of the channel and move inwardly towardseach other, maintaining their parallel positions.

Preferably, the channel forms part of a flexible assembly. The purposeof this is to allow the fastener to flex so that it can be used tofasten elements which may be curved or otherwise non-linear. To allowflexibility, it is preferred that the lockers, blockers, and the lockingtongue have relatively thin sections at their base, to allow verticalflexing to follow, for example, curved sections in a panel.

The fastener of the invention may be attached to the first element byany suitable means. It is particularly preferred that the fastener isretained in a retaining guide in the first element or in a rig attachedto the first element, the rig being bonded to the first element, forexample. It is preferred that the lockers are adapted to be retainedwithin a locking groove or other suitably shaped profile in the secondelement. When the fastener is locked, the lockers are engaged with thelocking groove and cannot be released while the blockers prevent thelockers from being pivoted into the channel. When the blockers are movedso that they no longer interfere with the lockers and the lockers canmove into the channel sufficiently to clear the locking groove, and thesecond element may be removed from the first element.

It is preferred that the locking tongue is caused to move between thelocking position and the unlocking position by material adapted tocontract when activated.

The material adapted to contract when activated is preferably shapememory alloy strip. Shape memory alloys are known and are usually madepredominantly or wholly of titanium and nickel. They may also includeother material, such as aluminium, zinc copper, and other similarmaterials. A shape memory alloy is capable of adopting one shape below apredetermined transition temperature and changing to a second shape onceits temperature exceeds the transition temperature. Conversely, when theshape memory alloy cools below the transition temperature, it is capableof adopting the first shape again. In connection with the presentinvention, the shape memory alloy preferably contracts when heated insitu. Shape memory alloy strip currently available, such as that soldunder the name Nitinol, is capable of contracting for many cycles byabout 3% when activated by heating.

Activation of the material adapted to contract when activated ispreferably achieved through electrical resistance heating, with a wirefeed to the assembly. Activation of the shape memory alloy strip can beinitiated from a central location, using the wiring system of, forexample, an aircraft or automobile. It is also within the scope of thisinvention that the activation is initiated by remote means, such as ahand held tool operating through the use of any suitable form of energy,including microwave, electro magnetic, magnetic, sonic, infra-red, radiofrequency and so on.

The scope of the invention is not necessarily limited to the use ofshape memory alloy. Other material may also be useful. Also, whileactivation may take place through heating, other means of activation maybe suitable and are within the scope of this invention.

While other configurations may also be suitable, it is preferred thatone shape memory alloy strip is used to move the tongue to the lockingposition and a second shape memory alloy strip is used to move thetongue to the unlocking position, so that the fastener of the inventionis bistable. When two strips are used, the fastener can be designed toremain in either the locked or the unlocked state until the opposingstrip is activated.

It may be desirable to link the locking and unlocking strips by a pushlink or other means, so that there is only a single actuator connectionwith the mechanism. This can permit the mechanism to be curved, whileconnected to a straight actuator.

The fastener is preferably a strip form of fastener. Even morepreferably, the fastener is made up of modules. For example, the minimummodule length may be 400 mm. For this size, the shape memory alloy stripmay have an active length of 300 mm and be of strip type 0.2×5 mm insection. Activation would require 24 amps at 13.8 volts for 1 second toheat and this could provide a 17 daN pulling force. Less amps may berequired if heating was spread over 3 to 5 seconds.

Modules may be linked together in any desirable way, such as by use ofan actuator plate which can attach adjoining modules.

In modular form, it would not be necessary to activate all modules atonce. Consequently, a small power supply may be adequate to activateeach module length.

In case of high ambient temperature or in an overheat situation, thefastener of the invention may include a failsafe element to ensure thefastener stays in the locked position. For example, the fastener mayinclude an unlock drive pin and in an overheat situation a failsafeelement may be able to move up and block the drive pin so that thefastener stays in the locked position.

Preferably, the shape memory alloy actuator is sealed against fluid anddust by a slip seal, which may be positioned in a recess and move backand forth with the locking and unlocking action of the actuator.

It will be appreciated that other actuators, apart from shape memoryalloy strip, may be used in connection with the fastener of theinvention, such as servomotors and hydraulic cylinders.

Preferably, two position sensors and one temperature sensor areintegrated within the fastener to monitor and control mechanismfunction. They provide the information that either the fastener is inthe locked state or that the fastener is in the unlocked state. Thetemperature sensor is used to measure internal ambient temperature tooptimize overall performance and to provide over and under operatingtemperature threshold shutdown protection. Activation of theover-temperature failsafe mechanism can also be part of thisarrangement.

Other advantages and aspects of the present invention will becomeapparent upon reading the following description of the drawings and thedetailed description of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a sectional side elevation of an embodiment of thefastener of the invention in situ, fastening a first element being aremovable panel and a second element being a fixed panel, the fastenerbeing in the locked position;

FIG. 2 depicts a plan view of the lockers and blockers of the fastenerof FIG. 1, in the locked position;

FIG. 3 corresponds to the embodiment in FIG. 1, except that the fasteneris shown in the unlocked position;

FIG. 4 is a plan view of the lockers and blockers in the unlockedposition;

FIG. 5 is a perspective view of an end of the fastener in the lockedposition;

FIG. 6 is a perspective view of the end of the fastener progressingtowards the unlocked position;

FIG. 7 is the same view as in FIGS. 5 and 6, but in the fully unlockedposition;

FIG. 8 is a partly exploded view of the embodiment in FIG. 5, showingthe locked position, and also showing part of the actuator, but with onestrip of lockers omitted for clarity;

FIG. 9 is a view corresponding to that in FIG. 8, for comparison withthat in FIG. 6;

FIG. 10 shows the embodiment of FIGS. 8 and 9, corresponding to FIG. 7;

FIG. 11 is a perspective view of the actuator in the previous Figures,in the locked position;

FIG. 12 shows the actuator in the unlocked position;

FIG. 13 is a plan view of a second embodiment of actuator suitable forthe fastener of the invention;

FIG. 14 is a side elevation of the actuator of FIG. 13;

FIG. 15 is an exploded view of an embodiment of modules of the fastener,showing architecture;

FIG. 16 is a detail from FIG. 15, illustrating how lockers and blockerscan be assembled in a module of the fastener;

FIG. 17 shows a node point between two fastener modules;

FIG. 18 further details of the linking of modules;

FIG. 19 shows in side elevation (locked position) how actuators can belinked between modules;

FIG. 20 is a perspective view of FIG. 19;

FIG. 21 shows detail of an actuator linkage, in the unlocked position;

FIG. 22 shows assembly of the fastener to a structure; and

FIG. 23 shows a detail from FIG. 22.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, fastener 10 (see FIGS. 2 and 4) is shown releasablyfixing a removable panel 12 to a fixed panel 14 (see FIGS. 1 and 3).

Retaining guide 18 is formed in rig bracket 16 to retain the elements offastener 10. Rig bracket 16 is bonded or otherwise affixed to fixedpanel 14.

Locking groove 20 is machined in removable panel 12, for engagement withfastener 10. Alignment of removable panel 12 with fixed panel 14 isassisted by tolerance positioning of retaining guide 18 in its seat andlocking groove 20 in removable panel 12.

With reference particularly to FIGS. 2, 4, 5 and 6, fastener 10 has achannel 22 formed between two strips 24 and 26 of lockers 28. Channel 22has a base formed by slidable locking tongue 30. Tongue 30 has blockers32. Preferably, lockers 28 are at 10 mm pitch (as are blockers 32) andspaces 36 between blockers 32 are large enough to accommodate lockers28.

When tongue 30 is drawn from the locking position shown in FIG. 5 to theunlocking position in FIG. 6, lockers 28 can pivot inwardly towards thecentre of channel 22, as shown in FIG. 7. Comparing this with FIGS. 1and 3, in the locked position lockers 28 are retained in locking groove20 by blockers 32 (FIGS. 1 and 2), but can be pivoted inwardly to clearlocking groove 20 when blockers 32 are moved out of register withlockers 28 (FIGS. 3 and 4) so as to unfasten panel 12 from panel 14.

Items 38, 40, 41 and 44 are described in connection with FIGS. 8 to 12,below.

FIGS. 8 to 12 show the elements of an embodiment of actuator forfastener 10. The actuator elements are contained within actuator casing38 which, in this embodiment, is made of aluminium. Plastic injectionmoulded liner 42 is used to support and insulate the electronics andshape memory alloy strips or ribbons of the actuator.

The actuator illustrated is bi-stable and has two shape memory alloy(SMA) ribbons 48 and 50. SMA ribbon 48 is used to unlock fastener 10,while SMA ribbon 50 is used to lock fastener 10. Fastener 10 can remainin either the locked or unlocked state until the opposing SMA ribbon isactivated. The SMA elements are internally linked by an SMA push link 41so that there is only one actuation connection mechanism. This allowsthe mechanism to be curved while linked to a straight actuator. SMAribbon 48 is fixed at end 60 (FIGS. 8 to 10), while SMA ribbon 50 isfixed at end 62 (FIG. 12).

Where fastener 10 is provided in modules (refer below), in the bi-stableembodiment it is not necessary to activate all modules at once. A smallpower supply may be used to activate each module length sequentially.

As can be seen in FIGS. 8, 9 and 10, strip 24 of lockers 28 has a bottomjoining section 52. Similarly, tongue 30 has a bottom joining section 54supporting blockers 32. Both joining sections 52 and 54 are in thisembodiment relatively thin, so that they allow vertical flex to follow,for example, curved sections in a panel.

Locker strips 24 and 26 and tongue 30 may both be made of metal toprovide a very strong joint for high load applications. Alternately, anengineering plastic may be used for locker strips 24 and 26 for lowerload requirements. Engineering analysis can establish appropriatematerial choices for a specific application.

The actuator elements also include unlock drive pin 44 (positionindicated in FIGS. 11 and 12) and lock drive pin 46.

Also visible in FIGS. 8 to 10 is overstress spring 56 and powerconductor loop 58.

As can be seen from the progression in FIGS. 8 through 9 and 10, aslocking tongue 30 is moved out of register with locker strip 24 (andlocker strip 26 not shown) blockers 32 clear lockers 28. When lockers 28are completely clear of blockers 32, lockers 28 pivot or tilt towardseach other. FIG. 10 illustrates this for lockers 28 on strip 24. Lockers28 on strip 26 (not shown) tilt towards lockers 28 on strip 24. In thisconfiguration, fastener 10 is no longer engaged in locking groove 20(refer FIG. 3) and removable panel or door 12 is released from fixedpanel 14.

Reference is now made to the embodiment in FIGS. 13 and 14. The samenumbers will be used to refer to the same or equivalent parts in theseFigures as used above.

Actuator casing 38 includes a well 64 (FIG. 14) to accommodateelectronics for the actuator elements. In the embodiment shown, fastener10 represents a module with a minimum module length of 400 mm. SMAribbons 48 and 50 have an active length of 300 mm and are of the ribbontype, being 0.2 mm×5 mm in section. Activation requires 24 amps at 13.8volts for 1 second to heat and can provide a 17 daN pulling force. Lessamps would be required if heating was carried out over 3 to 5 seconds.

Shown in FIG. 13 are four actuator casing screws 66 and SMA guide ribs68. The actuator assembly includes six actuator position fixing screws70, only one of which is labelled, for clarity.

SMA push link 41, which is also shown in FIG. 1, is indicated in FIG.13. SMA push link 41 links the SMA elements so that there is only oneactuation connection with the mechanism and so that the mechanism can becurved.

Included in FIG. 13 is failsafe element 72. This ensures that SMAlocking ribbon 50 stays in the locked mode in overheat conditions.Failsafe element 72 is positioned underneath drive pin 46 and, inoverheat conditions, failsafe element 72 moves up and blocks drive pin46 in the locked position.

Shown in FIG. 14 is slip seal 40. This is also shown in FIG. 1. Slipseal 40 is used to seal the actuator against fluid and dust. Slip seal40 is part of the actuator assembly and provides the linkage to drivepin 46. Slip seal 40 is positioned in a recess (not shown) in thealuminium support bracket and moves back and forth with the locking andunlocking action of the actuator.

FIG. 15 is an exploded view of an embodiment of modules of fastener 10and shows architecture. As can be seen from FIG. 15, removable panel 12has formed in it locking groove 20. Two modules of fastener 10A and 10Bare shown. It is to be understood that several fasteners 10 may belinked together.

In this embodiment, fixed panel 14 is provided with frame extension 74,instead of rig bracket 16. Frame extension 74 includes dove-tailedprotrusion 76 to fit into complementary groove 78 in fixed panel 14.Frame extension 74 includes channel 80 for locking tongue 30 withblockers 32 and strips 24 and 26 having lockers 28 (only one strip, 24,is shown for fastener 10A for clarity). Strips 24 and 26 and lockingtongue 30 are shown installed in channel 80 in fastener 10B.

Also illustrated in FIG. 15 are actuator slide 82, actuator plate 84,key plate 86 and actuator linkage 88. Refer to further discussion,below.

An embodiment of mode of assembly of a modular fastener 10 is shown inFIG. 16. Frame extension 74 is shown with channel 80. Each strip 24 or26 (24 is shown) with lockers 28 can be assembled into channel 80 fromabove as shown by arrow 89 or can be slid in from an end as indicated byarrow 90. Tongue 30 with blockers 32 may then be slid in from the end asindicated by arrow 92.

FIG. 17 shows how to chain one fastener 10A to a second fastener 10B ata node point 94. FIG. 17 shows actuator plate 84 as ready to be screwedinto channel 80 (actuator plate 84 is also shown in FIG. 15). Actuatorplate 84 includes a detail indicated at 96, to key actuator plate 84 tochannel 80. Actuator plate 84 also includes details, one of which isindicated at 98, in order to keep lockers 28 in place.

During assembly, tongue 30 and strips 24 and 26 (only one of which isshown in FIG. 17) are over travelled in order to assemble actuator plate84. Actuator plate 84 is screwed into channel 80. Tongue 30 and strips24 and 26 are then pushed back to their correct position.

Turning now to FIG. 18, this shows the use of actuator slide 82 andkeeper 86 in joining modules of fasteners 10A and 10B. Actuator slide 82keys into tongue 30 and into keeper 86. Shoulder 100 provides a stop tokeeper 86 to eliminate binding.

Keeper 86 is coated with Teflon or is made from a die cut Teflon pad.

FIGS. 19 and 20 show actuator slide 82 after insertion into keeper 86,in the locked position. As already mentioned, keeper 86 is coated withor made from Teflon. This reduces friction between keeper 86 andextension 74. Arrow 102 indicates direction of movement of tongue 30 bythe actuator.

FIG. 21 corresponds to the arrangement in FIGS. 19 and 20, butillustrates the unlocked position.

FIG. 22 shows the system assembled. Removable panel 12 is assembled tofixed panel 14 by means of fastener 10, which has been omitted fromFIGS. 22 and 23 for clarity. In this embodiment, there is an epoxyinterface between extension 74 and groove 78 on fixed panel 14. Theepoxy interface can extend to the side flanges indicated, so that asignificant surface area is available. Use of the epoxy interface canensure a flush mount, because tolerances can be taken up.

The description above relates to preferred embodiments of the presentinvention and is given by way of illustration. Changes, modificationsand variations may be made without departing from the spirit and scopeof the present invention.

Throughout the specification and claims the word “comprise” and itsderivatives is intended to have an inclusive rather than exclusivemeaning unless the context requires otherwise.

INDUSTRIAL APPLICABILITY

As will be readily appreciated by those skilled in the various arts, theinvention disclosed herein is not limited to the examples set out andhas wide application in many areas. The invention represents asignificant advance in the art of securing and releasing, particularlyin connection with strip fasteners.

1. A fastener adapted to releasably fix a first element and a secondelement, the fastener including: a channel having a plurality of spacedlockers forming opposed walls of the channel, the lockers being movableinto the channel; and a locking tongue having a plurality of spacedblockers and a base which forms the base of the channel, the tonguebeing movable within the channel between a locked position in which theblockers prevent movement of the lockers into the channel and anunlocked position in which the lockers are not prevented from movinginto the channel.
 2. The fastener of claim 1, wherein the spaced lockersforming opposed walls of the channel are on two strips and the spacedlockers are adapted to move into the channel by pivoting.
 3. Thefastener of claim 1, wherein the locking tongue is slidable along thebase of the channel.
 4. The fastener of claim 3, wherein the blockersand lockers are of similar dimension.
 5. The fastener of claim 4,wherein spaces between the blockers are of similar dimension to spacesbetween the lockers.
 6. The fastener of claim 5, which forms part of aflexible assembly.
 7. The fastener of claim 6, wherein the lockingtongue is caused to move between the locked position and the unlockedposition by material adapted to contract when activated.
 8. The fastenerof claim 7, wherein the material adapted to contract when activated isshape memory alloy ribbon.
 9. The fastener of claim 8, wherein the shapememory alloy ribbon is activated remotely or by hard wiring.
 10. Thefastener of claim 9, wherein the ribbon is activated by a hand held tooloperating through the use of a suitable form of energy chosen frommicrowave, electromagnetic, magnetic, sonic, infra-red, and radiofrequency energy.
 11. The fastener of claim 10, wherein a first shapememory alloy ribbon is used to move the tongue to the locked positionand a second shape memory alloy ribbon is used to move the tongue to theunlocked position.
 12. The fastener of claim 11, wherein the first andsecond shape memory alloy ribbons are linked by a push link.
 13. Thefastener of claim 12, which comprises means to lock the fastener if achosen temperature is exceeded.
 14. The fastener of claim 13, whichincludes a slip seal to seal against fluid and dust.
 15. The fastener ofclaim 14, which includes at least one sensor.
 16. The fastener of claim15, wherein the sensor is adapted to sense position and/or temperature.17. The fastener of claim 16 where a plurality of fasteners exists whenjoined as modules.